1. Field of the Invention
The disclosure relates generally to I/Q mismatch calibration, and, more particularly to devices of I/Q mismatch detection and compensation, and methods thereof.
2. Description of the Related Art
In a conventional wireless communication device such as a mobile phone, a digital baseband circuit provides a data stream of complex, digital baseband data to a transmitter, where the transmitted baseband data are often carried by an orthogonal transmitter signal represented by real components and imaginary components, or, in-phase (I) and quadrature (Q) components. In the transmitter, the real component of the transmitter signal is processed along a real-component circuit path and the imaginary component is processed along an imaginary-component circuit path, the circuit paths being parallel to each other. The digital and analog signal processing along the real-component and the imaginary-component circuit path are all in parallel, and may include multiplexing, filtering, power controlling, up-sampling and so on. The parallel signal processed transmitter signal is modulated to produce an analog radio frequency (RF) signal to be amplified and radiated into the air interface from an antenna, providing a base station of the communication system with communication data exchange.
Ideally, the real and imaginary components are processed along parallel circuit paths in the transmitter, and the circuit elements along one path are identical or matched with corresponding circuit elements along the other path. However, the corresponding circuit elements along the real and imaginary circuit paths may have differences from each other due to manufacturing process variations or geometrical layout differences, resulting in amplitude differences (“IQ gain mismatch”) and phase differences (“IQ phase mismatch”) between the real and imaginary components that are processed along the parallel paths and causing degraded signal quality.
Thus devices capable of I/Q mismatch calibration and methods thereof are needed to optimize transmitted signal quality.